Injection molding techniques have for some time been used for molding various parts, particularly of plastic. The injection molding apparatus conventionally consists of a mold formed of two halves typically, one or more pairs of fixed and movable bases (also referred to A and B mold bases respectively), which are mounted, respectively, on the top clamp plate and base support plate of the injection mold base mounted on the molding machine. Mold inserts, plural A and B mold inserts, which are adapted to fit into the fixed and movable sides of the machine usually have mold cavity defining means which are fixed in the bases in paired alignment, whereby upon closure of the base support plate toward the top clamp plate respective pairs of oppositely disposed mold inserts are brought together to close the mold cavities. Molding material is fed through the top clamp plate and A mold base thereon to a runner distribution system in the two mold sides, and molding material is delivered from such distribution system to respective mold cavities to mold parts. An ejector apparatus usually is provided to eject the molded parts from the opened mold cavities and the excess mold from the runner distribution system by means of ejector pins that extend, for example, through the base support plate, B mold base and B mold inserts mounted thereon.
Molds with removable mold inserts for mold frames are in use and are especially valuable for prototype or low production molding needs wherein the tooling is changed after relatively short time. However, the known molds of this type only allow for molding of several like-parts and does not allow for the molding of different parts. In order to mold a different part, the entire mold assembly must be changed. Because only the same mold inserts can be used at the same time, the molding of different parts still requires substantial changeover time. The need exists for an inexpensive and efficient mold injection apparatus that molds different parts at the same time and requires only minimal changeover time and machining operations.
Previous attempts to provide an injection molding apparatus containing removable interchangeable molding tools are described in U.S. Pat. No. 3,871,611 to Taketa ('611 patent); U.S. Pat. No. 4,828,479 to Pleasant ('479 patent); U.S. Pat. No. 4,959,002 to Pleasant ('022 patent); U.S. Pat. No. 5,302,103 to Brown ('103 patent); and U.S. Pat. No. 4,416,604 to Bender ('604 patent) all of which are incorporated herein by reference.
The '611 patent describes an improved mold having removable and replaceable cores (mold inserts or molding tools) and cavities, so that the need of providing a new mold base for every new part or product is eliminated. The arrangement of the mold is such that the cores and cavities can be easily and quickly removed and replaced with minimum down time of the molding apparatus.
The '479 patent describes a molding apparatus for use with removable inserts, described in patent '002. The molding apparatus comprises a cavity insert for the injection side and a core insert for the ejection side of a mold which are each shaped as a generally cylindrical, stepped body provided with circumferentially extending locking grooves and a liquid cooling or heating channel. Insert retainers and lifters having rotatable elements with locking tongues engaging the locking grooves clamp the inserts in the main mold frame. The main mold frame is provided with liquid conduits opening to opposite ends of the liquid channels so that the need for machine liquid conduits and channels for different inserts is avoided. Ejector tooling may be connected to the core insert for insertion and removal with it.
The '103 patent describes an injection molding machine which allows batch-conversions to be performed without significant machine downtime and/or the use of specialized tools. The molding apparatus provides a frame, an injection assembly coupled to the frame, a press assembly also coupled to the frame, a mold-mounting assembly coupled with the press assembly, and a mold pallet assembly adapted to be mounted to the press assembly by the mold-mounting assembly.
The '604 patent describes an injection molding system with plural pairs of mold inserts that are engageable for mold cavities mounted on mold bases, respectively on the relatively movable top clamp plate and base support plate of an injection molding machine. Rails on those bases hold the mold inserts in place in paired alignment. The '604 patent also describes a multiple stage ejecting and stripping apparatus to strip parts from mold cavities and a technique to eject the sprue before the parts.
None of the devices mentioned above comprise an injection molding apparatus which simultaneously molds different components while allowing the easy replacement of each different mold insert. The '611 patent describes removable mold inserts and a mold assembly which only allows for the simultaneous molding of like components. Similarly, the '479 patent describes a molding apparatus which allows for removable inserts but does not allow for the simultaneous molding of different components. The '103 patent describes a molding apparatus which down sizes batch conversions. Batch conversions refer to the process of changing sides of a mold assembly for the molding of various parts. Thus, the '103 patent does not allow for the simultaneous molding of different components but rather only down-sizes the time in which to change-over from one type of mold to another type of mold.
The above inventions only allow for the use of a uniform set of removable mold inserts. Variation of the parts to be molded requires changing the entire mold assembly. Simultaneous molding of different components can only be achieved by using two separate molding apparatuses, one mold assembly containing a particular uniform set of mold inserts and another mold assembly containing another particular set of uniform of mold inserts. For example, if Customer A desires an A part and customer B desires a B part, the only solution is to use two separate injection molding apparatuses, one containing a uniform set of mold inserts, each mold insert designed to mold an A part, and another molding apparatus containing a uniform set of mold inserts, each mold insert designed to mold a B part.
Consequently, there is a need in the art for a molding press injection apparatus with removable inserts or molding tools, that allows the simultaneous molding of different parts.
There is a further need in the art for an injection molding apparatus that quickly molds the different parts.
Finally, there is a further need in the art to simultaneously manufacture different components, which does not require a substantial change-over time.